[SPARC] Implement static static checking

[Eric Botcazou <ebotcazou at adacore dot com>]

This implements static stack checking in the SPARC back-end, i.e. checking of 
the static part of the stack frame in the prologue.  This is modelled on the 
Alpha back-end, but of course only activated by means of -fstack-check.

Tested on SPARC/Solaris and SPARC64/Solaris.  Applied on the mainline.


2010-07-02  Eric Botcazou  <ebotcazou@adacore.com>

	* expr.h (emit_stack_probe): Declare.
	* explow.c (emit_stack_probe): Make global.
	(anti_adjust_stack_and_probe): Fix comments.
	* config/sparc/linux.h (STACK_CHECK_STATIC_BUILTIN): Define to 1.
	* config/sparc/linux64.h (STACK_CHECK_STATIC_BUILTIN): Likewise.
	* config/sparc/sol2.h (STACK_CHECK_STATIC_BUILTIN): Likewise.
	* config/sparc/sparc.c: Include except.h.
	(sparc_emit_probe_stack_range): New function.
	(output_probe_stack_range): Likewise.
	(sparc_expand_prologue): Invoke sparc_emit_probe_stack_range if static
	built-in stack checking is enabled.
	* config/sparc/sparc-protos.h (output_probe_stack_range): Declare.
	* config/sparc/sparc.md (UNSPECV_PROBE_STACK_RANGE): New constant.
	(probe_stack_range): New insn.


-- 
Eric Botcazou

Index: expr.h
===================================================================
--- expr.h	(revision 161685)
+++ expr.h	(working copy)
@@ -645,6 +645,9 @@ extern void update_nonlocal_goto_save_ar
    says how many bytes.  */
 extern rtx allocate_dynamic_stack_space (rtx, rtx, int);
 
+/* Emit one stack probe at ADDRESS, an address within the stack.  */
+extern void emit_stack_probe (rtx);
+
 /* Probe a range of stack addresses from FIRST to FIRST+SIZE, inclusive.
    FIRST is a constant and size is a Pmode RTX.  These are offsets from
    the current stack pointer.  STACK_GROWS_DOWNWARD says whether to add
Index: explow.c
===================================================================
--- explow.c	(revision 161685)
+++ explow.c	(working copy)
@@ -43,7 +43,6 @@ along with GCC; see the file COPYING3.
 #include "output.h"
 
 static rtx break_out_memory_refs (rtx);
-static void emit_stack_probe (rtx);
 
 
 /* Truncate and perhaps sign-extend C as appropriate for MODE.  */
@@ -1355,7 +1354,7 @@ set_stack_check_libfunc (const char *lib
 
 /* Emit one stack probe at ADDRESS, an address within the stack.  */
 
-static void
+void
 emit_stack_probe (rtx address)
 {
   rtx memref = gen_rtx_MEM (word_mode, address);
@@ -1567,7 +1566,7 @@ anti_adjust_stack_and_probe (rtx size, b
       HOST_WIDE_INT isize = INTVAL (size), i;
       bool first_probe = true;
 
-      /* Adjust SP and probe to PROBE_INTERVAL + N * PROBE_INTERVAL for
+      /* Adjust SP and probe at PROBE_INTERVAL + N * PROBE_INTERVAL for
 	 values of N from 1 until it exceeds SIZE.  If only one probe is
 	 needed, this will not generate any code.  Then adjust and probe
 	 to PROBE_INTERVAL + SIZE.  */
@@ -1623,13 +1622,13 @@ anti_adjust_stack_and_probe (rtx size, b
 
       /* Step 3: the loop
 
-	  while (SP != LAST_ADDR)
-	    {
-	      SP = SP + PROBE_INTERVAL
-	      probe at SP
-	    }
+	 while (SP != LAST_ADDR)
+	   {
+	     SP = SP + PROBE_INTERVAL
+	     probe at SP
+	   }
 
-	 adjusts SP and probes to PROBE_INTERVAL + N * PROBE_INTERVAL for
+	 adjusts SP and probes at PROBE_INTERVAL + N * PROBE_INTERVAL for
 	 values of N from 1 until it is equal to ROUNDED_SIZE.  */
 
       emit_label (loop_lab);
@@ -1647,7 +1646,7 @@ anti_adjust_stack_and_probe (rtx size, b
       emit_label (end_lab);
 
 
-      /* Step 4: adjust SP and probe to PROBE_INTERVAL + SIZE if we cannot
+      /* Step 4: adjust SP and probe at PROBE_INTERVAL + SIZE if we cannot
 	 assert at compile-time that SIZE is equal to ROUNDED_SIZE.  */
 
       /* TEMP = SIZE - ROUNDED_SIZE.  */
Index: config/sparc/linux.h
===================================================================
--- config/sparc/linux.h	(revision 161685)
+++ config/sparc/linux.h	(working copy)
@@ -161,6 +161,9 @@ do {									\
 #undef CTORS_SECTION_ASM_OP
 #undef DTORS_SECTION_ASM_OP
 
+/* Static stack checking is supported by means of probes.  */
+#define STACK_CHECK_STATIC_BUILTIN 1
+
 #define MD_UNWIND_SUPPORT "config/sparc/linux-unwind.h"
 
 /* Linux currently uses RMO in uniprocessor mode, which is equivalent to
Index: config/sparc/sparc.md
===================================================================
--- config/sparc/sparc.md	(revision 161685)
+++ config/sparc/sparc.md	(working copy)
@@ -75,6 +75,7 @@ (define_constants
    (UNSPECV_CAS			8)
    (UNSPECV_SWAP		9)
    (UNSPECV_LDSTUB		10)
+   (UNSPECV_PROBE_STACK_RANGE	11)
   ])
 
 
@@ -6340,6 +6341,15 @@ (define_expand "probe_stack"
     = adjust_address (operands[0], GET_MODE (operands[0]), SPARC_STACK_BIAS);
 })
 
+(define_insn "probe_stack_range<P:mode>"
+  [(set (match_operand:P 0 "register_operand" "=r")
+	(unspec_volatile:P [(match_operand:P 1 "register_operand" "0")
+			    (match_operand:P 2 "register_operand" "r")]
+			    UNSPECV_PROBE_STACK_RANGE))]
+  ""
+  "* return output_probe_stack_range (operands[0], operands[2]);"
+  [(set_attr "type" "multi")])
+
 ;; Prepare to return any type including a structure value.
 
 (define_expand "untyped_return"
Index: config/sparc/sparc-protos.h
===================================================================
--- config/sparc/sparc-protos.h	(revision 161685)
+++ config/sparc/sparc-protos.h	(working copy)
@@ -75,6 +75,7 @@ extern const char *output_return (rtx);
 extern const char *output_sibcall (rtx, rtx);
 extern const char *output_v8plus_shift (rtx *, rtx, const char *);
 extern const char *output_v9branch (rtx, rtx, int, int, int, int, rtx);
+extern const char *output_probe_stack_range (rtx, rtx);
 extern bool emit_scc_insn (rtx []);
 extern void emit_conditional_branch_insn (rtx []);
 extern void print_operand (FILE *, rtx, int);
Index: config/sparc/sparc.c
===================================================================
--- config/sparc/sparc.c	(revision 161685)
+++ config/sparc/sparc.c	(working copy)
@@ -37,6 +37,7 @@ along with GCC; see the file COPYING3.
 #include "insn-attr.h"
 #include "flags.h"
 #include "function.h"
+#include "except.h"
 #include "expr.h"
 #include "optabs.h"
 #include "recog.h"
@@ -4005,6 +4006,160 @@ sparc_output_scratch_registers (FILE *fi
 #endif
 }
 
+#define PROBE_INTERVAL (1 << STACK_CHECK_PROBE_INTERVAL_EXP)
+
+#if PROBE_INTERVAL > 4096
+#error Cannot use indexed addressing mode for stack probing
+#endif
+
+/* Emit code to probe a range of stack addresses from FIRST to FIRST+SIZE,
+   inclusive.  These are offsets from the current stack pointer.
+
+   Note that we don't use the REG+REG addressing mode for the probes because
+   of the stack bias in 64-bit mode.  And it doesn't really buy us anything
+   so the advantages of having a single code win here.  */
+
+static void
+sparc_emit_probe_stack_range (HOST_WIDE_INT first, HOST_WIDE_INT size)
+{
+  rtx g1 = gen_rtx_REG (Pmode, 1);
+
+  /* See if we have a constant small number of probes to generate.  If so,
+     that's the easy case.  */
+  if (size <= PROBE_INTERVAL)
+    {
+      emit_move_insn (g1, GEN_INT (first));
+      emit_insn (gen_rtx_SET (VOIDmode, g1,
+			      gen_rtx_MINUS (Pmode, stack_pointer_rtx, g1)));
+      emit_stack_probe (plus_constant (g1, -size));
+    }
+
+  /* The run-time loop is made up of 10 insns in the generic case while the
+     compile-time loop is made up of 4+2*(n-2) insns for n # of intervals.  */
+  else if (size <= 5 * PROBE_INTERVAL)
+    {
+      HOST_WIDE_INT i;
+
+      emit_move_insn (g1, GEN_INT (first + PROBE_INTERVAL));
+      emit_insn (gen_rtx_SET (VOIDmode, g1,
+			      gen_rtx_MINUS (Pmode, stack_pointer_rtx, g1)));
+      emit_stack_probe (g1);
+
+      /* Probe at FIRST + N * PROBE_INTERVAL for values of N from 2 until
+	 it exceeds SIZE.  If only two probes are needed, this will not
+	 generate any code.  Then probe at FIRST + SIZE.  */
+      for (i = 2 * PROBE_INTERVAL; i < size; i += PROBE_INTERVAL)
+	{
+	  emit_insn (gen_rtx_SET (VOIDmode, g1,
+				  plus_constant (g1, -PROBE_INTERVAL)));
+	  emit_stack_probe (g1);
+	}
+
+      emit_stack_probe (plus_constant (g1, (i - PROBE_INTERVAL) - size));
+    }
+
+  /* Otherwise, do the same as above, but in a loop.  Note that we must be
+     extra careful with variables wrapping around because we might be at
+     the very top (or the very bottom) of the address space and we have
+     to be able to handle this case properly; in particular, we use an
+     equality test for the loop condition.  */
+  else
+    {
+      HOST_WIDE_INT rounded_size;
+      rtx g4 = gen_rtx_REG (Pmode, 4);
+
+      emit_move_insn (g1, GEN_INT (first));
+
+
+      /* Step 1: round SIZE to the previous multiple of the interval.  */
+
+      rounded_size = size & -PROBE_INTERVAL;
+      emit_move_insn (g4, GEN_INT (rounded_size));
+
+
+      /* Step 2: compute initial and final value of the loop counter.  */
+
+      /* TEST_ADDR = SP + FIRST.  */
+      emit_insn (gen_rtx_SET (VOIDmode, g1,
+			      gen_rtx_MINUS (Pmode, stack_pointer_rtx, g1)));
+
+      /* LAST_ADDR = SP + FIRST + ROUNDED_SIZE.  */
+      emit_insn (gen_rtx_SET (VOIDmode, g4, gen_rtx_MINUS (Pmode, g1, g4)));
+
+
+      /* Step 3: the loop
+
+	 while (TEST_ADDR != LAST_ADDR)
+	   {
+	     TEST_ADDR = TEST_ADDR + PROBE_INTERVAL
+	     probe at TEST_ADDR
+	   }
+
+	 probes at FIRST + N * PROBE_INTERVAL for values of N from 1
+	 until it is equal to ROUNDED_SIZE.  */
+
+      if (TARGET_64BIT)
+	emit_insn (gen_probe_stack_rangedi (g1, g1, g4));
+      else
+	emit_insn (gen_probe_stack_rangesi (g1, g1, g4));
+
+
+      /* Step 4: probe at FIRST + SIZE if we cannot assert at compile-time
+	 that SIZE is equal to ROUNDED_SIZE.  */
+
+      if (size != rounded_size)
+	emit_stack_probe (plus_constant (g4, rounded_size - size));
+    }
+
+  /* Make sure nothing is scheduled before we are done.  */
+  emit_insn (gen_blockage ());
+}
+
+/* Probe a range of stack addresses from REG1 to REG2 inclusive.  These are
+   absolute addresses.  */
+
+const char *
+output_probe_stack_range (rtx reg1, rtx reg2)
+{
+  static int labelno = 0;
+  char loop_lab[32], end_lab[32];
+  rtx xops[2];
+
+  ASM_GENERATE_INTERNAL_LABEL (loop_lab, "LPSRL", labelno);
+  ASM_GENERATE_INTERNAL_LABEL (end_lab, "LPSRE", labelno++);
+
+  ASM_OUTPUT_INTERNAL_LABEL (asm_out_file, loop_lab);
+
+   /* Jump to END_LAB if TEST_ADDR == LAST_ADDR.  */
+  xops[0] = reg1;
+  xops[1] = reg2;
+  output_asm_insn ("cmp\t%0, %1", xops);
+  if (TARGET_ARCH64)
+    fputs ("\tbe,pn\t%xcc,", asm_out_file);
+  else
+    fputs ("\tbe\t", asm_out_file);
+  assemble_name_raw (asm_out_file, end_lab);
+  fputc ('\n', asm_out_file);
+
+  /* TEST_ADDR = TEST_ADDR + PROBE_INTERVAL.  */
+  xops[1] = GEN_INT (-PROBE_INTERVAL);
+  output_asm_insn (" add\t%0, %1, %0", xops);
+
+  /* Probe at TEST_ADDR and branch.  */
+  if (TARGET_ARCH64)
+    fputs ("\tba,pt\t%xcc,", asm_out_file);
+  else
+    fputs ("\tba\t", asm_out_file);
+  assemble_name_raw (asm_out_file, loop_lab);
+  fputc ('\n', asm_out_file);
+  xops[1] = GEN_INT (SPARC_STACK_BIAS);
+  output_asm_insn (" st\t%%g0, [%0+%1]", xops);
+
+  ASM_OUTPUT_INTERNAL_LABEL (asm_out_file, end_lab);
+
+  return "";
+}
+
 /* Save/restore call-saved registers from LOW to HIGH at BASE+OFFSET
    as needed.  LOW should be double-word aligned for 32-bit registers.
    Return the new OFFSET.  */
@@ -4193,6 +4348,9 @@ sparc_expand_prologue (void)
   /* Advertise that the data calculated just above are now valid.  */
   sparc_prologue_data_valid_p = true;
 
+  if (flag_stack_check == STATIC_BUILTIN_STACK_CHECK && actual_fsize)
+    sparc_emit_probe_stack_range (STACK_CHECK_PROTECT, actual_fsize);
+
   if (sparc_leaf_function_p)
     {
       frame_base_reg = stack_pointer_rtx;
Index: config/sparc/linux64.h
===================================================================
--- config/sparc/linux64.h	(revision 161685)
+++ config/sparc/linux64.h	(working copy)
@@ -287,6 +287,9 @@ do {									\
 #undef CTORS_SECTION_ASM_OP
 #undef DTORS_SECTION_ASM_OP
 
+/* Static stack checking is supported by means of probes.  */
+#define STACK_CHECK_STATIC_BUILTIN 1
+
 #define MD_UNWIND_SUPPORT "config/sparc/linux-unwind.h"
 
 /* Linux currently uses RMO in uniprocessor mode, which is equivalent to
Index: config/sparc/sol2.h
===================================================================
--- config/sparc/sol2.h	(revision 161685)
+++ config/sparc/sol2.h	(working copy)
@@ -188,4 +188,7 @@ along with GCC; see the file COPYING3.
 #define PUSHSECTION_FORMAT	"\t.pushsection\t\"%s\"\n"
 #endif
 
+/* Static stack checking is supported by means of probes.  */
+#define STACK_CHECK_STATIC_BUILTIN 1
+
 #define MD_UNWIND_SUPPORT "config/sparc/sol2-unwind.h"